Nokia has a plan in its back pocket should a deal with Microsoft fall through, or the forthcoming Windows Phone 8 software update fail to generate interest, according to Nokia's board chairman.

Speaking on his debut television appearance, F-Secure's founder and former chief executive Risto Siilasmaa, who became Nokia's board chairman in May, defended the move to Microsoft's Windows Phone, which replaced the ailing Symbian operating system last year.

But he said Nokia has a "contingency plan" should the forthcoming Windows Phone 8 "fail to live up to expectations," according to a report by Finnish newspaper Yle Uutiset.

Nevertheless, Siilasmaa remains confident that the Windows Phone-powered Nokia smartphones would be a success following the company's move to put all its eggs in the same basket with the Microsoft-provided mobile operating system.

What the contingency plan could be, however, remains unknown.

"Symbian's market share has come down close to zero," making a move to a partner mobile operating system inevitable, and a return to Symbian almost impossible. CNET UK considered Android as a possibility, but noted the phone giant would find it difficult to stand out among the crowd of existing Android partners such as Samsung and HTC.

Since Siilasmaa's hiring, Nokia's share price has fallen by a third. In the past year alone, the Finnish-based phone maker has seen its share price fall by more than 80 percent, with its market cap collapsing from $78 billion to $7.8 billion in three years.